This invention relates to a tape cassette provided with a pair of reel hubs, a magnetic recording tape wound around the reel hubs, and a housing containing the reel hubs and the magnetic recording tape, and more specifically to a tape cassette provided with magnetic recording tape guide means for controlling the running direction of the magnetic recording tape travelling from one of the reel hubs to the other and for controlling the position of the tape relative to the housing across the thickness thereof.
A housing of a prior art tape cassette includes a pair of spaced apart holding plates disposed in parallel with the each other, a front wall coupling the holding plates and having openings for the insertion of a magnetic head and a pinch roller, a rear wall facing the front wall and coupling the holding plates, and a pair of side walls facing each other and coupling the holding plates and the front and rear walls. Further, a magnetic recording tape guide means of the prior art tape cassette includes a first tape guide member mounted on one of the two holding plates in the vicinity of the point of intersection between one of the two side walls and the front wall, and a second tape guide member mounted on one of the holding plates in the vicinity of the point of intersection between the other of the side walls and the front wall. A magnetic recording tape fed out from one of the two reel hubs contained in the housing to the other is first guided in its running direction by the first tape guide member, and travels toward the second tape guide member. Namely, the tape runs along the front wall of the housing between the first and second tape guide members. Then, the magnetic recording tape is guided in its running direction by the second tape guide member, travels to the other reel hub, and is wound thereon. At the same time, the magnetic recording tape is defined in its position relative to the housing across the thickness thereof by the first and second tape guide members.
When the prior art cassette is mounted on a magnetic recording tape operation apparatus, such as a tape recorder, and the magnetic recording tape is driven from one of the reel hubs to the other, a magnetic head comes in contact with the tape between the first and second tape guide members. Also, the magnetic recording tape is touched by a tape guide member of the magnetic recording tape operating apparatus in the vicinity of the magnetic head. The tape guide member of the apparatus defines the position of the tape relative to the housing across the thickness thereof.
In such prior art cassette, the path of the magnetic recording tape between the supply-side reel hub and the magnetic head is relatively short. In such short tape path, moreover, the magnetic recording tape is defined in its position relative to the housing across the thickness thereof by only the two tape guide members. The use of such few tape guide members in the short path will change the relative position of the tape suddenly. The sudden change of the tape position will produce excessive torsional stress at the contact portions of the magnetic recording tape which are contacted with the two guide members. The excessive torsional stress will distort or damage the tape. Further, the sudden change of the tape position will reduce the accuracy regarding the definition of the tape position. The reduction of the accuracy will shift the position of a track of the magnetic recording tape. In reproducing information from the tape track by using the magnetic head after recording the information on the tape track by means of the magnetic head, the shifting of the track position will distort the information to be reproduced.